The invention relates to power management in a computer system.
The manufacturers of personal computers, particularly portable computers, strive to reduce both component size and power consumption in these computers. The sizes of the transistors used to form computer components tend to decrease by approximately 70% every 18 months. However, as component sizes decrease, the leakage current increases. This can increase total power consumption associated with these components increases. In general, the power consumption caused by leakage current increases by a factor of approximately ten with each 70% decrease in component size.
One technique for reducing power consumption in a computer involves reducing the frequency at which the computer""s processor is clocked when the processor is idle. Using current manufacturing techniques, the amount of leakage current in a processor is very small in comparison to the amount of power consumed in clocking the processor""s storage elements. Therefore, reducing the processor""s clocking frequency leads to a comparable reduction in power consumption. However, as the components in the processor become even smaller, leakage current will account for a much greater portion of power consumption. As a result, reducing the processor""s clocking frequency will produce smaller gains in power consumption than are possible today.
A computer processor includes a plurality of storage elements, such as logic gates and flip-flops, that are interconnected in a first configuration during normal operation of the processor. A plurality of selector elements connected to the storage elements are used to rearrange the storage elements into a second configuration upon entry into a low-power mode of operation.
In general, the storage elements, when rearranged into the second configuration, form a chain through which data passes serially for storage in a storage device, such as a memory device or a hard drive.
Other embodiments and advantages will become apparent from the description and claims that follow.